Carburetor



'Oct. 20, 1931.

- Filed Dec. 20,

C. F. JOHNSON CARBURETOR 1928 2 Sheets-Sheet 1 l :r l'l jz W INVENTOR.

A TTORNEY.

Oct. 20, 1931. c. F. JOHNSON CARBURETO R 2 Sheets-Sheet 2 Filed Dec.

INVENTOR.

ATTORNEY.

Patented on. 20, 1931 OHESTEB F. JOHNSON, OE DETROIT, IICHTGAN oennnnn'ron Application filed December 20, 1928. Serial No. 827,409.

The present invention relates to carburetors for internal combustion engines and more particularly to valve operating mechanism therefor.

Heretofore, in carburetor construction, it

has been customary to provide means for choking the air inlet passage or opening in order to provide a rich mixture for starting the engine. Such means usually consists of a valve in the air passage operable by theoperator to cut down the inflow of air to such a degree as to very greatly lower the pressure in the mixing chamber and thereby draw thereinto a much greater than ordinary flow of liquid fuel. However, if the main throttle valve in the mixture passage leading to the engine is closed, as frequently happens, passage of mixtures by such valve may be less than the volume of inflow to the mixing char 90 her and consequently the pressure in the latter may not be lowered sufiiciently to properly enrich the mixture or the flow past the main throttle and may not be sufiicient to carry the cold mixture into the engine.

Among the objects of the present invention, therefore, is to overcome this difliculty and provide means for insuring a suflicient throttle opening to have the desired results when the choke is being used.

Other objects will readily occur to those skilled inthe art upon reference to the following description and the accompanying drawings in which Fig. 1 is a side elevation of a carburetor embodying the present invention,

Fig. 2 is a section on line 22 of Fig. 1.

Fig. 3 is a central vertical section in the plane of Fig. 1, and

Fig. 4 is an end elevation as from the left of Fig. 1.

In the drawings there is shown a carburetor provided with the usual float bowl 10 and a mixing chamber indicated as a whole at 11 to which fuel is supplied from the carburetor through a suitable Venturi tube 12 and to which air is supplied through anopening 13 ordinarily controlled by means of a hingedly mounted valve 14; held shut means of a light compression resisting spring .15 when the motor is dead. .A conventional dash pot 16 is connected to the valve through a link 17 to prevent flutter. The flow of mixture from the carburetor to the engine is regulated by means of the throttle valve 18.

As is well known in the carburetor art, it is desirable to choke the carburetor for start-- ing purposes so as to supply the engine with a very rich mixture and this choking action is accomplished in the present carburetor by means of the plunger 20 operable by the lever arm 21 to compress the spring 15 to hold the valve 14 shut. This lever arm 21 is loosely mounted on the shaft 22, which is rotatable by means of-the crankarm 23, connected by suitable linkage to the choke button. Arm 21 is operable by means of a second arm 25, also carried on rotatable shaft 22 but keyed or fixed thereto, so as to be rotatable therewith.

The arm 25 has fixed therein a pin 26 adapted to coact with a slot 27 in a lever 28 which lever is rotatably mounted on the shaft 29 of the throttle valve 18, and. the latter shaft 29 carries fixed thereto an arm 30 provided with an adjustable stop 31 cooperating with a suitable surface 32 on lever 28, so that when the latter is moved in a clockwise direction, it tends to rotate the throttle in a similar direction, the throttle shaft however may be operated independently of lever 28, as will be obvious.

The member 25 keyed to shaft 22 carries at one side a short leaf spring which operates in conjunction with a lateral extension 41 on the lever arm 21 so that when the shaft v 22 is rotated by the crank arm 23 it carries with it the member 25, which by means of the spring abutment 40 striking the extension 41, rotates the lever 21 so as to compress spring 15 to-hold shut the valve 14, the resilience of springs 15 and 40 will, however, permit a slight opening of the valve when the suction in the carburetor becomes great enough to overcome the spring pressure.

The lever 21 is preferably provided with an adjustable stop member 45 by means of which, in an indirect manner, the tension on the spring 15 of the valve 14 may be adjusted and the plunger 20 is likewise pro vided with a spring 46 counteracting spring 40 to hold the lever against the spring 40.

Likewise the adjustable stop member 31 may be used to fix the closed position of the throttle 18 so as to provide for greater or less opening.

Further, it is preferred to provide the lever 28 at its free end with a small extension 50 which rests on the shaft 22 when in idle position and fixes the idle position of the lever 28.

In the operation of the carburetor, assuming the engine to be cold and it is desired to start, the choke button is pulled out as far as possible. A link connected to the choke button and crank 23 rotates the latter counterclockwise and with it shaft 22 and arm 25. Spring 4:0 carried thereby will then cause abutment 41 to move to the left, causing rotation of lever 21 on its pivotal shaft 22 in a counterclockwisedirection tending to raise plunger 20 to compress spring 15 and to hold valve 14 against the 0 ening 13. The a1r control valve 14 there ore has not only its spring 15 put under increased tension, but the part 20 is raised sufiiciently to maintain the valve 14- closed during the cranking operation, that is, before the engine starts to fire and the suction acting on the valve is thereby greatly increased. Through the resilience of the spring 40 howeverthe valve lei may still open a short way by the increased suction thereon when the engine has begun to fire.

In the operation of pulling out the choke button and consequently moving the crank 23 shaft 22 and arm 25, the first movement of the latter begins to actuate the lever 28 and at the same time to move to slightly more open position the throttle valve 18. The effect of this is that, when the choke is being used to any extent whatever to change the richness of the mixture, the throttle valve is likewise controlled to prevent its entirely closing to idle position. When the choke valve is in normal running position, that is, with the choke button entlrcly in and the throttle in idle position, the hookalp through arm 25 is, of course, inoperative. When, however, the choke control is moved even a short distance and before it begins to enrich the mixture, the throttle valve is also moved a short distance from its idle position so as to compensate for the temperature condition of the motor. When it is necessary to enrich the mixture through use ofthe choke it will also be necessary to slightly increase the throttle opening over and above that used when the motor is operating normally. In the present device the air control valve and the throttle are coordinated so that they function in accordance with the temperature of the motor.

Now having described the invention and the preferred forms of embodiment thereof, it is to be understood that the said invention is to be limited not to the specific details herein described and illustrated but only by the scope of the claims which follow.

I claim 1. In a carburetor having a throttle and a choke valve, sprin means tending to hold the choke valve close means for operating the choke valve, means for operating the throttle valve, and means connectin the two last men-.

tioned sets of means where y when the choke valve is being moved to closing position the throttle valve is moved to an open position, said connecting means including a pivotally mounted arm operatively connected to the choke valve operating means, and a pivotally mounted link operatively connected to the throttle valve operating means, the arm and the link being operatively connected to each other.

2. In the carburetor having a throttle and a choke valve, spring means tending to hold the choke valve closed, means for operating the choke valve, means for operating the throttle valve, and means connecting the two last mentioned sets of means whereby when the choke valve is being moved to closing position the throttle valve is moved to an open position, said connecting means including a (pivotally mounted arm operatively connecte to the choke valve operating means,

and a pivotally mounted link operatively connected to the throttle valve operating means, the arm and the link being operatively connected to each other, the operative connection between the arm and the choke valve operating means including a pivotally mounted element, one of whose ends is adapted to engage the means which tends to maintain the choke valve closed, and the other of whose ends is adapted to be moved by the moving arm.

3. In a carburetor having a throttle and a choke valve, spring means tending to hold the choke valve closed, means for operating the choke valve, means for operating the throttle valve, and means connecting the two last mentioned sets of means. whereby when the choke valve is being moved to closing position the throttle valve is moved to an open position, said connecting means ineluding a pivotally mounted arm operativelyconnected to the choke valve operating means, and a pivotally mounted link operatlvely connected to the throttle valve operatmg means, the arm and the link being operatively connected to each other, the operative connection between the arm and the choke valve operating means including a pivotally mounted element, one of whose ends is adapted to engage the means which tends to maintain the choke valve closed, and the other of whose ends is adapted to be moved by the moving arm, there being a spring connection between the moving arm and the last mentioned end of the pivotally mounted element.

4. In a carburetor having a throttle and a choke valve, spring means tending to hold the choke valve closed, means for operating the choke valve, means for operating the throttle valve, and means connecting the two last mentioned sets of means whereby when the choke valve is being moved to closing position the throttle valve is moved to an open position, said connecting means including a pivotally mounted arm operatively connected to the choke valve operating means, and a pivotally mounted link operatively connected to the throttle valve operating means, the arm and the link being operatively connected to each Ether, b a pin and slot 'oint.

. CHES ER F. JOHNS N. 

